Saddle advice for an upright bike

I’m trying to get my girlfriend into biking more. She enjoys it, but we’ve had a hard time finding a comfortable saddle for her. We’ve tried a gel saddle (which I advised against but she thinks I’m biased against comfort and for performance), then we tried a harder cruiser saddle and finally I got her a Brooks B68S. She hasn’t biked in a long time so she doesn’t really know what kind of pain is normal as you’re getting your bum used to biking but it sounds like what she’s experiencing isn’t just the usual soreness under the sit bones. It sounds like there is a lot of pressure on the flesh/muscles behind the sit bones. She’s been dealing with it for a while and she’s not getting used to it.

I’m not sure if this is a function of her upright position or the wrong saddle. Is it even possible to sit on your sit bones when your torso is upright? I’ve never ridden an upright bike with any regularity but when I sit on one, I feel like my weight is resting on my muscles, not bones. I'm out of ideas on how to help her be more comfortable. Any advice would be appreciated.